A conventional method for a regular and a preliminary tuning of a keyboard musical instrument comprises the following steps of:
(1) vibrate a string;
(2) judge a tonal pitch from sonic vibrations thereof; and
(3) based on the judgment made in step (2), turn a tuning pin to carry out the tuning operation.
Usually, tuning of a string by this method is so performed that the above-listed tuning steps (1)--(3) are repeated several times to complete the tuning.
According to the aforementioned conventional method, in the case of a piano equipped with 230 strings, for example, it is necessary to individually tune each string, as a result of which much time and labor is required to tune a piano. Furthermore, when tuning step (1) is to be performed for a key which actuates a plurality of strings in unison, it is necessary to apply pieces of rubber, felt or the like to other strings so as to prevent those strings from generating sound by vibration when the key is stricken for tuning of a string other than those strings. This makes the tuning operation very complex. In addition, since a string-exciting mechanism is required in order to carry out tuning step (1), the tuning should be performed in such a condition that an action mechanism has been incorporated therein. This limits the freedom of selecting the sequence of tuning steps. In tuning step (2), it is a general practice that, for comparison, the reference string is vibrated simultaneously with the string to be tuned and a tune pitch thereof is judged from the frequency of a beat tone so generated, so that a comparatively high expertness in the art is required to perform this step. Accordingly, in actuality all tuning operations are almost exclusively performed by professional tuning experts.